The healthy hormonal development of young girls can be affected by many things, but now researchers at Mount Sinai School of Medicine have found that exposure to phenols, phthalates and phytoestrogens can disrupt the timing of pubertal development, and put girls at risk of health complications later in life.

Phenols, phthalates and phytoestrogens are among chemicals known as endocrine disruptors, which interfere with the body’s endocrine, or hormone, system. They are found in a wide range of consumer products, such as nail polishes, where they increase durability, and in cosmetics, perfumes, lotions, and shampoos, where they carry fragrance. Some are used to increase the flexibility and durability of plastics such as PVC, or are included as coatings on medications or nutritional supplements to make them timed-release.

The researchers analysed the impact of exposure to environmental agents in a study that included 1,151 girls between 6-8 years old from New York, greater Cincinnati and Northern California. Dr. Mary Wolff, Professor of Preventive Medicine and Oncological Sciences at Mount Sinai School of Medicine said: “Research has shown that early pubertal development in girls can have adverse social and medical effects, including cancer and diabetes later in life. Our research shows a connection between chemicals that girls are exposed to on a daily basis and either delayed or early development.”

The data showed that high exposure to certain chemicals was associated with early breast development, with the strongest links seen with phthalates and phytoestrogens. Of particular concern are the phthalates found in personal products such as lotion and shampoo, especially those with fragrance, as they were related to earlier breast and pubic hair development.

Dr Wolff commented: “We believe that there are certain periods of vulnerability in the development of the mammary gland, and exposure to these chemicals may influence breast cancer risk in adulthood.”

Confirming previous studies, the researchers also found that body-mass index (BMI) played a role in the onset of puberty with about a third of the girls in the study being considered overweight. A high BMI is also an indicator of early breast development so the role of diet in hormonal development is also important.

This is the first study to examine the effects of these chemicals on pubertal development and appeared in the online journal Environmental Health Perspectives in April 2010.